Thermionic converter.



W. TL BIRDSALL.

THERMIONIC CONVERTER.

APPLICATION FILED IAN. 10, 1916.,

Patented J an. 14, 1919.

WITNESSES: INVENTOR Wf/fmd mmm/ M BY A/ ATTORNEY Bill tlti

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WJELFRED T. BIRDSALL, 0F MONTCLAIR, NEW JERSEY,

ASSIGNQR TQ WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

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Specification of Letters Patent. Y Patented J an. 14:, 1919.

Application ma January 10, 1916. trial No. 71,388,

' To all whom it may concern:

Be it known that I, WILFRED T. BmnsALL, a citizen of the United Sta es, and a resident of Montclair, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Thermionic Converters, of which the following is a specification. 1 My invention relates to thermionic vacuum-type converters, and it has for its object to provide a device of the character described that shall be simple in manufacture and highly effective in operation.

The single figure of the accompanying drawing is a side view, partially in section and partially in elevation, of a converter embodying a preferred form of my invention.

In the operation of vacuum-type converters, it has been proposed to operate at an extremely high vacuum with a cathode heated to incandescence in order that there be a pure electron emission and no collisions with residual gas such as might result in the production of positive ions and consequent bombardment and deterioration of the cathode. A device of this character is disexample, on page 193 of a work entitled Conduction of Electricity Tit rough Gases by J. J. Thomson (1906).

Apparatus of the character above de scribed has many advantageous features in operation but it is extremely difficult to manufacture because of the abnormally high vacua which must be produced and maintained. Furthermore, the freedom from neutral-gas collisions permits the electrons to move with such high velocity that they tend to vaporize the material of the electrodes and to liberate occluded gases.

It has been found that the impact of an electron upon a molecule of one of the socalled noble gases, that is to say, the rare gases of the atmosphere such, for example, as argon, neon, crypt-on, xenon, etc, instead of resulting in the production of a pair of ions, as is the case with ordinary gas molecules, results in a rebound of the impacting electron, with little or no loss of energy, by reason of the apparently elastic nature of the noble gases. This phenomenon was first noted by 15 ranck and Hertz, Berz'chtc clcr Dcutschcn Pkysikahlschen Gesellschaft, Heft 2, 1913. lit was further noted and discussed by Bergen Davis in the Physical Review, vol. 7, No. 4, April 18, 1916, page 489, and vol. 7 N o. 5, of the same periodical for May, 1916, particularly on pages 501 and 509, and has been experimentally verified by myself. By filling a vacuum-type converter, therefore, with noble gases, a pure electron discharge may be maintained, with resultant desirable operating characteristics and, at the same time, the difliculties incident to producing and maintaining the high vacua hitherto employed in apparatus of this character are removed.

In my copending application, Serial No. 25,866, filed May 4, 1915, and assigned to the Westinghouse Lamp Company, I have disclosed a vacuum-type converter wherein the cathode takes the form of a blast of superheated vapor. According to the present invention, the. operation of a converter of the pure-electron-emission type, employing an incandescent filament. as a cathode, may be much improved by directing a blast of superheated vapor upon said cathode. I am not prepared to explain the resultant action but there is apparently a much more pro? nounced electronic emission and an increase in the current-carrying capacity, possibly due, in part, to the mechanical action of the blast in sweeping electrons toward the anode.

Referring to the accompanying drawing for a more detailed understanding of my invention, I show the container of a vacuum-type converter at 1", said container being composed, preferably, of glass or quartz. The container 1 is provided with an anode 2 composed of a vaporizable reconstructing materlal, such for example as mercury or suitable amalgams and with a cathode 4 in the form of a filament; composed, preferably, of tungsten or molybdenum. The cathode 4: 1s provided with a pair of leading-in wires 5-5 which are connected to a source of heating'current 6 that is so adjusted as to maintain the cathode 4 in a state of incandescence. The anode 2 and the cathode 4 are connected,

terminals of a source of alternating current respectively, to the.

7, and rectified current flows through a load The interior of the container 1 is first highly exhausted and thoroughly treated out and is then charged with a noble gas or with a mixture of noble gases.

A blast of superheated vapormay be maintained upon the cathode t by taking material from theanode 2 through a tube 9, passing said material through a boiler 10 and ejecting it from a nozzle 11 upon the cathode, whence said material returns to the anode 2.

In the ope ation of the device, substantially no positive ions are produced by the collisions of the electrons emitted at the cathode at with gas molecules, but said electrons proceed to the anode 2 and produce an exceedingly stable and satisfactory are suitable for current rectification or for other purposes. The effectiveness of operation of the device is greatly enhanced by the presence of the blast established from the nozzle 11.

I desire it to be distinctly. understood that the presence of a noble gas within a converter of the pure-electron-discharge type is beneficial, as above pointed out, in the absence of a cathode blast.

Throughout this description, I have explained the action of my device in accordance with the theory which seems most plausible in view of the present knowledge of the underlying phenomfena. I desire it to be distinctly understood, however, that I do not confine myself to said theory of operation but. merely present the same as an aid to an understanding of the invention.

\Vhile I have shown my invention in its preferred form, it will be obvious to those skilled in the art that it is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. In a vacuum-type converter, the combination with an anode, of a cathode, means for maintaining said cathode at incandescence, means for causing a blast of superheated 'apor to impinge upon said cathode, and means for maintaining an electromotive force between said electrodes.

2. In a vacuum-type converter, the combination with an anode, of a cathode, means for maintaining said cathode at incandescence. means for causing a blast of superheated metallic vapor to impinge upon said cathode, and means for maintaining an electromotive force between said electrodes;

3. In a vacuum-type converter, the com- .bination with an anode composed of vaporiza'ble reconstructing material, of a cathode, means for maintaining said cathode at incandescence, means for causing a blast of superheated vapor formed from the material of said anode to impinge 'upon said cathode, and means for maintaining an electromotive force between said electrodes.

'4. In a vacuum-type converter, the combination with an anode, of a filamentary cathode, means for passing heating current through said cathode to maintain the same at incandescence, means for causing a blast of superheated metallic vapor to impinge upon said cathode, and means for maintaining an electromotive force between said electrodes.

5. In a vacuum-type converter, the combination with an anode composed of vaporizable reconstructing material, of a filamentary cathode, an auxiliary source of current connected to said cathode for maintaining the same at incandescence, means for directing upon said cathode a blast of superheated vapor formed from the material of said anode, and means for maintaining an electromotive force between said electrodes.

(3. The combination with a vessel containing a noble gas, of an anode and a cathode therein, means for maintaining said cathode at incandescence, means for causing a blast of superheated vapor to impinge thereupon, and means for maintaining an electromotive force between said electrodes.

7. The combination with a vessel containing a noble gas, of an anode therein composed of a vaporizable reconstructing material, a filamentary cathode, means for passing current through said cathode to maintain it at incandescence, means for causing a blast of superheated vapor of said anode material to impinge upon said cathode, and means for maintaining an electromotive force between said electrodes.

In testimony whereof, I have hereunto subscribed my name this 30th day of December 1915.

WILFRED T. BIRDSALL. 

